没个函数都错在与结构体有关的地方，下面是报错。
  void  search()            /***查找函数***/
{   
      
    int i,n,k,w1=1,w2,w3;   
    struct   Hotel   s;   
    n=load();   
    do   
    {   
        w2=-1;   
    do   
    {   
        k=-1;   
        printf("\n\nEnter ID_card that you want to search! ID_card:");                        
        scanf("%s",&s.Client_list.ID_card);                                                      /***输入需要查找的身份证号***/
        for(i=0;i<n;i++)   
            if(strcmp(s.Client_list.ID_card,Room [i].Client_list.ID_card)==0)                    /***串比较函数，若表达式等于0，则两串相等***/
            {  


warning C4047: 'function' : 'const char *' differs in levels of indirection from 'int '
C:\Program Files\Microsoft Visual Studio\MyProjects\program\pro.c(183) : warning C4024: 'strcmp' : different types for formal and actual parameter 1
C:\Program Files\Microsoft Visual Studio\MyProjects\program\pro.c(183) : warning C4047: 'function' : 'const char *' differs in levels of indirection from 'int '
C:\Program Files\Microsoft Visual Studio\MyProjects\program\pro.c(183) : warning C4024: 'strcmp' : different types for formal and actual parameter 2
C:\Program Files\Microsoft Visual Studio\MyProjects\program\pro.c(209) : error C2143: syntax error : missing ';' before 'type'
C:\Program Files\Microsoft Visual Studio\MyProjects\program\pro.c(211) : error C2143: syntax error : missing ';' before 'type'
C:\Program Files\Microsoft Visual Studio\MyProjects\program\pro.c(316) : warning C4047: 'function' : 'const char *' differs in levels of indirection from 'int '
C:\Program Files\Microsoft Visual Studio\MyProjects\program\pro.c(316) : warning C4024: 'strcmp' : different types for formal and actual parameter 1
C:\Program Files\Microsoft Visual Studio\MyProjects\program\pro.c(316) : warning C4047: 'function' : 'const char *' differs in levels of indirection from 'int '

把完整的代码贴出来吧，现在没弄懂你的意思呢。

 #include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#define NUM 100
struct Client
{
    char Name[20];
    int Sex;
    int Age;
    char ID_card[20];                     /***身份证号***/
    int year;
    int month;
    int date;                             /***住店时间***/
};
struct Hotel
{
    int Room_ID;                           /***房间号***/
    char Tel[15];                          /***电话号码***/
    int Price;                             /***住房单价***/
    int Sign;                              /***标记是否为空房间***/
    struct  Client Client_list;            /***实现两个结构体的嵌套***/
}Room[NUM];
 void  search()            /***查找函数***/
{   
      
    int i,n,k,w1=1,w2,w3;   
    struct   Hotel   s;   
    n=load();   
    do   
    {   
        w2=-1;   
    do   
    {   
        k=-1;   
        printf("\n\nEnter ID_card that you want to search! ID_card:");                        
        scanf("%s",&s.Client_list.ID_card);                                                      /***输入需要查找的身份证号***/
        for(i=0;i<n;i++)   
            if(strcmp(s.Client_list.ID_card,Room [i].Client_list.ID_card)==0)                    /***串比较函数，若表达式等于0，则两串相等***/
            {   
                k=i;   
                w2=1;   
                printf_one(k);   
                break;                                                                          /***跳出for循环体***/
            }   
            if(k==-1)   
            {   
                printf("\n\nNo exit!");   
                printf("\n\ndo you try again ?\n\t1).again 2).No and back ");   
                scanf("%d",&w1);   
                if(w1!=1)  menu();                                                              /***返回主菜单***/
            }   
    }while(k==-1&&w1==1);                                                                       /***重试时继续执行循环体***/
      
    if(w2==1)   
    {   
        printf("\n\nDone\n");   
        printf("\nWhat do you want to do?\n\t1).Search another 2).Back to menu ");   
        scanf("%d",&w3);   
        if(w3!=1)  menu();                                                                         /***返回主菜单***/  
    }   
    }while(w3==1);         

也就是我在查找函数内定义的struct hotel s 总被报错

 #include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#define NUM 100
struct Client
{
    char Name[20];
    int Sex;
    int Age;
    char ID_card[20];                     /***身份证号***/
    int year;
    int month;
    int date;                             /***住店时间***/
};
struct Hotel
{
    int Room_ID;                           /***房间号***/
    char Tel[15];                          /***电话号码***/
    int Price;                             /***住房单价***/
    int Sign;                              /***标记是否为空房间***/
    struct  Client Client_list;            /***实现两个结构体的嵌套***/
}Room[NUM];
 void  search()            /***查找函数***/
{   
      
    int i,n,k,w1=1,w2,w3;   
    struct   Hotel   s;   
    n=load();   
    do   
    {   
        w2=-1;   
    do   
    {   
        k=-1;   
        printf("\n\nEnter ID_card that you want to search! ID_card:");                        
        scanf("%s",&s.Client_list.ID_card);                                                      /***输入需要查找的身份证号***/
        for(i=0;i<n;i++)   
            if(strcmp(s.Client_list.ID_card,Room [i].Client_list.ID_card)==0)                    /***串比较函数，若表达式等于0，则两串相等***/
            {   
                k=i;   
                w2=1;   
                printf_one(k);   
                break;                                                                          /***跳出for循环体***/
            }   
            if(k==-1)   
            {   
                printf("\n\nNo exit!");   
                printf("\n\ndo you try again ?\n\t1).again 2).No and back ");   
                scanf("%d",&w1);   
                if(w1!=1)  menu();                                                              /***返回主菜单***/
            }   
    }while(k==-1&&w1==1);                                                                       /***重试时继续执行循环体***/
      
    if(w2==1)   
    {   
        printf("\n\nDone\n");   
        printf("\nWhat do you want to do?\n\t1).Search another 2).Back to menu ");   
        scanf("%d",&w3);   
        if(w3!=1)  menu();                                                                         /***返回主菜单***/  
    }   
    }while(w3==1);         

 #include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#define NUM 100
struct Client
{
    char Name[20];
    int Sex;
    int Age;
    char ID_card[20];                     /***身份证号***/
    int year;
    int month;
    int date;                             /***住店时间***/
};
struct Hotel
{
    int Room_ID;                           /***房间号***/
    char Tel[15];                          /***电话号码***/
    int Price;                             /***住房单价***/
    int Sign;                              /***标记是否为空房间***/
    struct  Client Client_list;            /***实现两个结构体的嵌套***/
}Room[NUM];
 void  search()            /***查找函数***/
{   
      
    int i,n,k,w1=1,w2,w3;   
    struct   Hotel   s;   
    n=load();   
    do   
    {   
        w2=-1;   
    do   
    {   
        k=-1;   
        printf("\n\nEnter ID_card that you want to search! ID_card:");                        
        scanf("%s",&s.Client_list.ID_card);                                                      /***输入需要查找的身份证号***/
        for(i=0;i<n;i++)   
            if(strcmp(s.Client_list.ID_card,Room [i].Client_list.ID_card)==0)                    /***串比较函数，若表达式等于0，则两串相等***/
            {   
                k=i;   
                w2=1;   
                printf_one(k);   
                break;                                                                          /***跳出for循环体***/
            }   
            if(k==-1)   
            {   
                printf("\n\nNo exit!");   
                printf("\n\ndo you try again ?\n\t1).again 2).No and back ");   
                scanf("%d",&w1);   
                if(w1!=1)  menu();                                                              /***返回主菜单***/
            }   
    }while(k==-1&&w1==1);                                                                       /***重试时继续执行循环体***/
      
    if(w2==1)   
    {   
        printf("\n\nDone\n");   
        printf("\nWhat do you want to do?\n\t1).Search another 2).Back to menu ");   
        scanf("%d",&w3);   
        if(w3!=1)  menu();                                                                         /***返回主菜单***/  
    }   
    }while(w3==1);